On heavy particle-wall interaction in axisymmetric plasma discharges Articles uri icon

publication date

  • August 2021

start page

  • 085004

issue

  • 8

volume

  • 30

International Standard Serial Number (ISSN)

  • 0963-0252

Electronic International Standard Serial Number (EISSN)

  • 1361-6595

abstract

  • The effects of heavy particle-wall interaction on a cylindrical plasma source discharge are investigated, through hybrid particle-in-cell/fluid simulations. The bulk plasma is considered quasineutral with isothermal electrons, and with no secondary electron emission from the walls. The neutral gas wall reflection model is shown to play a major role in determining the conditions for a self-sustained and stationary plasma discharge. A hysteresis cycle on the injection mass flow rate is found when neutrals deviate from a purely diffuse reflection at the walls, with the mass utilization efficiency changing up to 20% between purely specular and diffuse scenarios. However, as the ratio of ionization mean free path to macroscopic length is decreased, the neutral-wall reflection model becomes irrelevant. Finally, even small deviations from unity of the ion energy accommodation coefficient at the walls are seen to have a major impact on both the ion and neutral distribution functions, and ultimately the mass utilization efficiency. This behavior stresses out the importance of a precise experimental determination of this parameter for accurate simulations.

keywords

  • particle-in-cell; plasma-wall interaction; hysteresis cycle; low-pressure plasma; discharge; plasma source